1. Field of the Invention
The present invention concerns a public telecommunication terminal, in particular for mobile radio networks.
2. Description of the Prior Art
The present invention is applicable to modern mobile radio networks of the GSM ("Global System for Mobile communications") type, for example.
A public or private telecommunication terminal generally includes, in addition to telecommunication means proper, a man-machine interface including means (for example a keypad) enabling the user to enter control data for the terminal.
This control data naturally includes data that is essential to the provision of a basic service provided by the network concerned, such as dialing data in particular, but may include other data, especially in modern telecommunication networks.
In particular, in mobile radio networks such as the GSM network, for example, the data may include such other data relating to the control of so-called supplementary services.
These supplementary services include, for example:
outgoing call barring, PA1 outgoing call restriction (e.g. barring of international calls), PA1 incoming call barring, PA1 diversion of incoming calls to a different number, etc.
The fact that the user of a terminal can control the supplementary services, to which he requires access through the keypad on the terminal represents a problem when the terminal is a public terminal, namely that a terminal of this kind may be totally or partially inoperative after a maneuver of this kind.
An essential aim of the present invention is to solve this problem.
In mobile radio networks such as the GSM network, for example, in which information is stored in a card such as the "SIM" ("Subscriber Identity Module") card, for example, inserted into the terminal to enable it to be used, this control data may also include data relating to control of services associated with the card. As these services may modify or delete information stored in the card, a card inserted into a public terminal may entail the risk of the terminal becoming totally or partially inoperative as a result of their activation. A problem of a similar nature to that previously mentioned in connection with the supplementary services then arises; for this reason the following description lumps together these two types of services, namely supplementary services and card-related services, with particular reference to the "SIM" card, under the generic name of additional services.